1. Field of the Invention
The present invention relates to subpad supports in web format and belt format polishing apparatus. Particularly, the present invention relates to subpad supports including nonadhesive subpad securing elements and to polishing apparatus including the subpad supports. The present invention also relates to assemblies including a subpad and a subpad support of the present invention, as well as to methods of assembling a subpad with, securing a subpad to, removing a subpad from, and replacing a subpad on a subpad support of the present invention.
2. State of the Art
Web format polishing apparatus typically include a wafer support and a polishing pad. The wafer support is typically configured to hold a semiconductor wafer, to bring the wafer into contact with the polishing pad, and to rotate the wafer while the wafer is in contact with the polishing pad so as to create friction between the wafer and the polishing pad and, thereby, effect polishing of one or more layers on the wafer. As used herein, the term “polishing” encompasses removal of material from a semiconductor wafer. “Polishing,” as used herein, need not achieve a certain surface finish or planarity. A subpad, located on the opposite side of the polishing pad from the wafer support, is configured to prevent the formation of defects on a wafer secured to the wafer support during polishing thereof, as well as to cushion the polishing pad and wafer being polished so as to prevent damage to the wafer during polishing. The subpad is held in place by a subpad support and, conventionally, has been secured to the subpad supports by way of an adhesive material.
Fresh portions of a web format, film-type polishing pad are supplied by a supply reel of the web format polishing apparatus, while used portions of the web format polishing pad are taken up on a take-up reel of the apparatus. Typically, the positions of supply reels and take-up reels on conventional web format polishing apparatus are fixed relative to the remainder of these apparatus.
As a subpad wears, it must be replaced. Typically, in order to remove a subpad from a web format polishing apparatus, the web format polishing pad must either be cut or slack formed in the polishing pad by, for example, loosening the web format pad from the supply reel of the polishing apparatus without winding the pad around the take-up reel. Creating slack in a web format polishing pad facilitates pulling of the polishing pad away from the subpad. When a web format polishing pad is cut or given slack, it is common that a portion of the polishing pad is damaged and, thus, that portion of the polishing pad is wasted. In addition, as the subpad is typically secured to the subpad support with an adhesive material, removal of the subpad from the subpad support is often very difficult since the subpad may rip or need to be scraped from the subpad support.
Belt format polishing apparatus are very similar to web format polishing apparatus, with the major exception being that the polishing pad is in the format of a continuous belt that may be recycled, rather than a web that is supplied from a supply reel and, after use, taken away on a take-up reel. In order to gain access to a subpad of a belt format polishing apparatus, the belt format polishing pad is removed from the polishing apparatus, which is time consuming and may result in damage to the pad, or the pad may be stretched, which may also damage the pad. Damage that may occur to a belt format polishing pad as a subpad is removed and replaced is, however, even more costly than similar damage to a web format polishing pad because a damaged belt format polishing pad must be completely replaced.
The inventor is not aware of a subpad support to which a subpad may be nonadhesively secured and from which a subpad may be readily removed. Moreover, the inventor is not aware of a web format or belt format polishing apparatus configured to facilitate subpad removal and replacement without a significant potential for damaging the polishing pad.